Rotating wing aircraft



July 30, 19 0- H. FOCKE ROTATING WING AiRCRAFT Filed May 19, 1938 3Sheets-Sheet l July 30, 1940. H. FOCKE ROTATING WING AIRCRAFT Filed May19, 1958 s Sheeis-Sheet 2 flti'arneys i lam July 30, 1940. H, FOCKE2209,879

ROTATING WING AIRCRAFT Filed May 19, 1938 3 Sheets-Sheet 3 Q lm/entor:

W64 MKQaZ-Z Manley-s PatentedJuly 30, 1940.

UNITED STATES ROTATING WING AIRCRAFT Henrich Focke, Bremen, GermanyApplication May 19, 1938, Serial No. "208,917 In Germany August 16, 193711 Claims.

This invention relates to improvements in rotating wing aircraft inwhich the blade-incidence of the rotor is variable.

In order to provide for the safe descent of such aircraft upon thefailure of the power unit, it is known to provide means, controlledeither automatically or by the pilot, for reducing the angles ofincidence of the rotor blades. This is necessary because the incidencewhich is necessarily rather large for helicopter positions must bereduced to rotating wing conditions if an auto-rotation of the rotor anda normal gliding flight are to be ensured.

Aircraft of the kind in question with a power capacity capable of givingsteep ascent and considerable forward speed, have heretofore sufiered adisadvantage. This is primarily due to the necessity for having a fixedtransmission ratio between the engine and rotor or ro'tors in order I toavoid the employment of complicated driving mechanism. When there is anincrease in speed 01' climb and forward flight the torque consumption ofthe rotor or rotors falls off considerably.

Thus, therevis a danger of the engine running up I to excessive speedsduring this condition, or that the engine speed will fall away duringhovering flight when the torque consumption of the rotor increases.Therefore, the engine would not develop its full output just at themoment when N such output is, relatively, most urgently required.

This defect is avoided by the present invention which has for itsprincipal object to provide means whereby, duringchanging speed offlight,

86 the torque consumption of the rotor or rotors is adapted to thetorque output of the engine or engines when helicopter positionsprevail.

A further object is to provide for an additional variation of the angleof incidence of the rotor blades, over and above that which is eifectedwhen changing over from the rotating wing condition to the helicopterposition, so that the correct Yet another object of the invention is toprovide movable securing means for the normal blade-incidence controlmember at one of the limit positions of its movement when changing overfrom rotating wing condition to helicopter ,5 position and to put thismovable securing means in operative connection with one of theadditionalcontrols referred to.

Further objects and features of the invention will appear from thefollowing description having 10 reference to the annexed drawings, theexamples therein given being merely illustrative and not restrictive. Inthe drawings:

Figure 1 is a diagrammatic view of a rotor (only one blade being shown)under the additional con- .1 trol of blade-incidence adjusting meanssensitive to air speed through the blade-swept area or to dynamicpressure due to such air speed.

Figure la is a fragmentary view similar to Figure 1 showing a differentposition of the air 29 speed sensitive means.

Figure 2 is a diagrammatic view illustrating additional blade-incidenceadjusting means com-. prising a governor.

Figure 3 is a similar view illustrating addi- $5 tional blade-incidenceadjusting means interlinked with gas throttle adjustment.

Figure 4 is a similar view illustrating-additional blade-incidenceadjusting means operated by a transmission from the joy-stick. 30

Figure 5 is a similar view illustrating additional blade incidenceadjusting means operated by a transmission from a normal. aircraftcontrol such as the fin adjusting mechanism.

In Figure 1, the angle of incidence of the blade .35 I is varied by acrank arm 2 and link 3 connected with a disc I having ball bearingconnection with a screw spindle 5. The last-named works in a. nut part 6and carries a pulley l which can be turned by an endless cable 8 lappedaround all) it and also around a return pulley I4. A hand lever I0 isengaged with the cable 8, sothat by moving the lever H1, in onedirection or the other through the angle indicated, the pulley is turnedin one direction or the other, causing the spindle 5 to rise or fall.Due to the tran's-- mission 4, 3, 2 such vertical movements of thespindle 5 produce blade rocking and change of angle of blade-incidencein known manner.

The lever It carries a latch or pawl H which I can be engaged with anotch in a fixed block 9 at one limit of the angular movement, thislimit corresponding with a blade setting of small angle of incidence tosuit the rotating wing condition. At the opposite limit the latch I Ican be engaged with a notch in a block I2, this limit corresponding witha blade setting of increased angle of incidence to suit the helicopterposition.

In accordance with the objects of the invention, the block 12 is notfixedly connected to the aircraft, but is itself also movable, say inthe direction of swinging of the control lever l0. It is adjusted bymeans of a bell-crank lever l3 and a rod l5 connected with a piston l6which works in a cylinder IT. The Pitot tube 20 disposed in the stream2| of the rotor is connected to the cylinder I! by means of the tubularpassage IS. The spring l8 counteracts upward movement of the piston 18.

If now the velocity of flow through the blade swept area increases,then, due to the increasing dynamic pressure, the piston l8 movesupwardly and the block l2 travels to the right and increases the angleof the blade incidence even more than it had already been increased bythe adjustment of the lever ill from the rotating wing condition to thehelicopter position. The torque taken by the lifting screw, which hadfallen off due to the increase of velocity of air stream is thereforeincreased again. By correct selection of the adjustment movement, thesize of piston and its loading spring, engine speed is maintained inspite of the changing conditions. The reverse takes place upon decreaseof the velocity of air stream. If the regulating forces from the amicpressures in the screw stream do not suffice, naturally a suitable relaymay be interposed.

The arrangement takes a form similar to that described above when theforward speed is to be utilised for the control. There is the solediiIerence that the Pitot tube is then disposed horizontally, as shownby 22, 23 in Figure la, and is directed towards the wind of travelindicated by dotted arrows at 24.

In Figure 2 the speed of revolution is employed directly for thecontrol. A centrifugal governor 25 is provided which receives its drivethrough the shafts 26 from the rotors. Depending upon the speed, whichthus depends upon the speed of revolution of the rotor or rotors, theadjusting member, in other words the notched block 12, is adjustedthrough the bellcrank lever l3 to the right or the left depending uponwhether the speed of revolution of the rotors tends to increase ordecrease due to increase or decrease of speed. The blade angle is variedby this adjustment and this in turn counteracts the increase or decreaseof the revolution speed as the case may be.

In Figure 3, the gas throttle 21 itself is employed for the control.Since, in general, opening of the gas throttle indicates a higher speed,it follows that the object of the speed adaptation is approximately alsoachieved by connecting the gas throttle to the notched block l2 in suchfashion that an increase in the gas simultaneously sets a larger bladeangle. Here, the same effect is achieved as in Figure 2. Certainly,there is a subsidiary effect, for a larger blade'angle is obtained withfull gas even in the case of vertical climbing. This, however, is notundesirable, for even in this case the larger blade angle represents abetter adaptation to the climbing condition.

In Figure 4 the additional control is associated with the joy stickbecause, generally speaking, a pressing forward of the control stick 3|means theattainment of higher speed. Consequently the notched block I2is connected through the bell crank lever l3 and, for example, cables2., 29 with the cross-piece 30 of the control stick 3|,

this moreover in such fashion that the block l2 travels to the rightupon pressing forward the stick ll. Thus, here also, higher speed isaccompanied by an adjustment which produces a larger blade angle. Thisexample is only possible in the case of an aircraft without adjustmentof the fixed horizontal fins.

In a machine having horizontal fin adjustment, the pilot can utilisethis to achieve for himself, in the diflerentconditions of flight, asfar as possible, the same position of the control stick which isphysically most comfortable for him. He will therefore make appropriateuse of the fin adjustment. In such machines, the arrangement of Figure 5is to be preferred. Here, the notched block I2 is connected to the finadjustment 32 in such fashion that with larger angles of incidence ofthe fins, which is equivalent to putting the nose of the aircraft downand, therefore, to higher speed, the notched block I2 is again moved tothe right and thus increases the blade angle. This may be effected byincluding a crank disc 33 in the control cable system 32 for thehorizontal fins. This disc then drives a rod 34 which in turn adjuststhe bell crank lever l3 and, therewith, also the notched block l2. Inthis case also, as in all theother cases, the adaptation to the speedcondition for the time being is effected.

I claim:

1. In a rotating wing aircraft, a rotating wing with variable incidenceblades, hand operated means for positively setting the incidence angleof said blades to either of two predetermined positions corresponding tohelicopter and autogiro conditions of the rotating wing, respectively,first means for locking and unlocking said setting means in theirautogiro position, second means for locking and unlocking said settingmeans in their helicopter position and means for positively readjustingthe position of said second means within a small range about saidpredetermined helicopter position, whereby the torque consumption of therotating wing can be suited to the engine output in the helicoptercondition, under variable helicopter flying conditions.

2. In a rotating wing aircraft, a rotating wing with variable incidenceblades, hand operated means for positively setting the incidence angleof said blades to either of two predetermined positions corresponding tohelicopter and autogiro conditions of the rotating wing, respectively.fi st means for locking and unlocking said setting means in theirautogiro position, second means for locking and unlocking said settingmeans in their helicopter position, a control organ associated with theengine and having a part whose position is determined by an enginecondition, and means associating said part and second means forpositively readjusting the position of said second means within a smallrange about said predetermined helicopter position in a manner toprovide substantially optimum torque consumption of the rotating wing inthe helicopter condition, under variable flying conditions.

3. In a rotating wing aircraft, a rotating wing with variable incidenceblades, hand operated means for positively setting the incidence angleof said blades to either of two predetermined positions corresponding tohelicopter and autogiro conditions of the rotating wing, respectively,first means for locking and unlocking said setting means in theirautogiro position, second means for locking and unlocking said settingmeans in their helicopter position, a control organ having a partdepending for its position on the aerodynamical forces in the airstreamoi the rotatingwing,andmeans undercontrolofsaidpart for positivelyreadjusting the position of said second means within a small range aboutsaid predetermined helicopter position in a manner tov providesubstantially optimum torque consumption of the rotating wing in thehelicopter condition, under variable flying. conditions.

4. In a rotating wing aircraft, a rotating wing with variable incidenceblades, hand operated means for positively setting .the incidence angleof said blades to either of two predetermined positions corresponding tohelicopter and autogiro conditions of the rotating wing, respectively,first means for locking and unlocking said setting means in theirautogiro position, second means for locking and unlocking said settingmeans in their helicopter position, a cylinder and piston arrangement,means for operating said arrangement by the dynamic pressure exerted bythe air stream of the rotating wing, against a resilient counterforceforming partof said -airangement, and means under control of saidarrangement for positively readjusting the position of said second meanswithin a small range about said predetermined helicopter position in amanner to provide substantiallyibptimum torque consumption of therotating wing in the helicopter condition, under variable flyingconditions.

5. In a rotating wing aircraft, a rotating wing with variable incidenceblades, hand operated means for positively setting the incidence angleof said blades to either of two predetermined positions corresponding tohelicopter and autogiro conditions of the rotating wing, respectively,first means for locking and unlocking said setting means in theirautogiro position, second means for locking and unlocking said settingmeans in their helicopter position, a cylinder and piston arrangement,means for operating said arrangement by the dynamic pressure exerted bythe vertical component of the air stream of the rotating wing, against aresilient counterforce forming part of said arrangement, and means undercontrol of said arrangement for positively readJusting the position ofsaid second means within a small range about said predeterminedhelicopter position in a manner to provide substantially optimum torqueconsumption of the rotating wing in the helicopter condition, undervariable flying conditions.

6. In a rotating wing aircraft, a rotating wing with variable incidenceblades, hand operated means for positively setting the incidence angleof said blades to either of two predetermined positions corresponding tohelicopter and autogiro conditions of the rotating wing, respectively,first means for locking and unlocking said setting means in theirautogiro position, second means for locking and unlocking said settingmeans in their helicopter position, a cylinder and piston arrangement,means for operating said arrangement by the dynamic pressure exerted bythe horizontal component of the air stream of the rotating wing, againsta resilient counter- ,force forming part of said arrangement, and meansunder control of said arrangement for pdsitively readjusting theposition of said second means within a small range about saidpredetermined helicopter position in a manner to provide substantiallyoptimum torque consumption of the rotating wing in the helicoptercondition, under variable flying conditions.

7. In a rotating wing aircraft, a rotating wing with variable incidenceblades, hand operated means for positively setting the incidence angleof said blades to either of two predetermined positions corresponding tohelicopter and autogiro conditions of the rotating wing, respectively,

first means for locking and unlocking said setting means in theirautogiro position, second means for locking and unlocking said settingmeans in their helicopter position, a control organ depending on theengine speed, and means under control of said organ for positivelyreadjusting the position of said second means within a small range aboutsaid predetermined helicopter position in a manner to providesubstantially optimum torque consumption of the rotating wing in thehelicopter condition, under variable flying conditions;

8. In a rotating wing aircraft, a rotating wing with variable incidenceblades, hand operated means for positively setting the incidence angleof said blades to either of two predetermined positions corresponding tohelicopter and autogiro conditions of the rotating wing, respectively,

first means for locking and unlocking said setting means in theirautogiro position, second means for'locking and unlocking said settingmeans in their helicopter position, means for adjusting the rate of fuelsupply to the engine of the aircraft, and means under control of thesaid fuel supply adjusting means of the engine for positivelyreadjusting the position of said second means within a small range aboutsaid predetermined helicopter position, whereby the torque consumptionof the rotating wing can be suited to the engine output in thehelicopter condition, under variable helicopter flying conditions.

9. In a rotating wing aircraft, a rotating wing with variable incidenceblades, an elevator control, hand'operated means for positively settingthe incidence angle of said blades to either of two predeterminedpositions corresponding to helicopter and autogiro conditions of therotating wing, respectively, first means for locking and unlocking saidsetting means in their autogiro position, second means for locking andunlocking said setting means in their helicopter position and meansunder control of said elevator control for positively readjusting theposition of said second means within a small range about saidpredetermined helicopter position, whereby the torque consumption of therotating wing can be suited to the engine output in the helicoptercondiition, under variable helicopter flying condit ons.

10. In a rotating wing aircraft, a rotating wing with variable incidenceblades, adjustable horizontal fins, a manually adjustable fin controldevice, hand operated means for positively setting the incidence angleof said blades to either of two predetermined positions corresponding tohelicopter and autogiro conditions of the rotating wing, respectively,first means for locking and unlocking said setting means in theirautogiro position, second means for locking and unlocking said settingmeans in their helicopter position and means whose position is dependenton the position of said fin control device 'for positively readjustingthe position of said second means within a small range about saidpredetermined helicopter position, whereby the torque consumption of therotating wing can be suited to the engine output in the helicoptercondition, under variable helicopter flying conditions.

11. In a rotating wing aircraft, a rotating wing with variable incidenceblades, a lever for positively setting the incidence angle of saidblades to either or two predetermined positions correspending tohelicopter and autogiro conditions of the rotating wing, respectively, astationary block including locking means for locking and unrocking saidlever in its autogiro position, an adjustable block including lockingmeans for locking and unlocking said lever in its helicopter po-

